This invention relates generally to circuit breakers and, more particularly, to thermal circuit breakers.
Circuit breakers are electrical circuit protective devices that interrupt a flow of current when the current exceeds a specified value, sometimes referred to as an overcurrent value. In an overcurrent condition, the circuit breaker rapidly separates a pair of contacts that normally conduct the current. Circuit wiring and associated circuit components may therefore be isolated from potentially damaging and undesirable exposure to excess currents. Conventionally, circuit breakers are either thermally or magnetically actuated.
One type of known thermal circuit breaker includes a nonconductive housing with conductive line and load contact terminals therein for electrical connection to a circuit to be protected. A temperature responsive element, sometimes referred to as thermal trigger element, is extended across the line and load contacts, and when the breaker is connected to an energized circuit, current flows between the breaker contacts through the trigger element in normal operation. Current flow through the trigger element heats the trigger element, and when current flow exceeds a predetermined level, the trigger element trips, deflects, or deforms to an activated position separated from each of the breaker contacts, thereby breaking the current through the breaker and protecting load side electrical devices.
Additionally, some thermal circuit breakers include manual reset and manual trip features to interrupt the breaker circuit independently of thermal conditions. Implementing such features can lead to relatively complicated constructions that increase manufacturing and assembly costs of the breaker.
In one aspect, a circuit breaker is provided comprising a nonconductive housing, a first breaker contact within said housing, and a trigger element comprising a second breaker contact located within said housing. The trigger element is thermally activated to separate said second breaker contact from said first breaker contact in an overcurrent condition. A nonconductive reset mechanism is located in said housing and configured for sliding actuation to prevent electrical connection between said first breaker contact and said second breaker contact after said trigger element has activated.
In another aspect, a circuit breaker is provided. The circuit breaker comprises a nonconductive housing, a first breaker contact within said housing, and a trigger element comprising a second breaker contact located within said housing. The trigger element is thermally activated to separate said second breaker contact from said first breaker contact in an overcurrent condition. A nonconductive reset element is located in said housing and configured for sliding actuation to prevent electrical connection between said first breaker contact and said second breaker contact after said trigger element has activated, and a manual trip element comprises opposite legs pivotally mounted to said housing. The opposite legs of the manual trip element contact said trigger element and separate said first and second breaker contact when said trip element is pivoted.
In another aspect, a circuit breaker comprises a nonconductive housing and first and second terminal blades extending from said housing. A first breaker contact is located within said housing and is in electrical contact with said first blade terminal. A trigger element comprises a second breaker contact located within said housing, and the second breaker contact is in electrical contact with said second blade terminal. The trigger element is thermally activated to separate said second breaker contact from said first breaker contact in an overcurrent condition. A reset element comprises opposite legs in sliding engagement with said first and second blade terminals and a nonconductive portion extending between said opposite legs. The nonconductive portion is positionable between said first breaker contact and said second breaker contact to prevent electrical connection therebetween after said trigger element has activated. A manual trip element comprises opposite legs and a cross member therebetween, and the legs are pivotally mounted to said housing. The trip element legs contact the trigger element and separate the first and second breaker contacts when said manual trip element is pivoted.